Plateaus, Plains, and Basins — Reading Comprehension

Plateaus, plains, and basins are some of the largest flat landforms on Earth. These features shape continents, influence ecosystems, and affect human activities. Understanding how these landforms form helps scientists explain Earth's surface changes and predict how landscapes may evolve in the future.

Formation of Plateaus
Plateaus are elevated, flat regions that rise sharply above the surrounding land. Two main processes create plateaus: volcanic activity and tectonic uplift. Volcanic plateaus, such as the Columbia Plateau in the United States, form when thick layers of lava flow over large areas and cool into rock. The Columbia Plateau covers over 160,000 square kilometers, created by repeated lava floods nearly 17 million years ago. In contrast, tectonic plateaus like the Colorado Plateau or the Tibetan Plateau form when forces inside the Earth push large sections of the crust upward. These plateaus often have steep edges and may be cut by deep canyons, such as the Grand Canyon, which rivers carve over millions of years. Scientists use geological evidence and rock dating to understand these processes.

Plains: Flat, Low-Lying Areas
Plains are broad, flat areas that usually lie at low elevations. There are several types: coastal plains (formed from former seafloors that have risen above sea level), interior plains (created by sediment deposited over ancient rocks), and lake plains (the floors of dried-up lakes). The Great Plains of North America stretch for over 1,800 miles and are filled with thick sediment washed down from the Rocky Mountains. These sediments can be hundreds of meters thick. Plains are important for agriculture because their soils are often rich and deep, supporting crops and grasslands. Scientists study sediments and fossils in plains to reconstruct ancient environments.

Basins: Low Areas Surrounded by Higher Land
Basins are low-lying regions often surrounded by hills or mountains. Basins can form by the downwarping of the Earth's crust, the spreading apart of land (called rifting), or the erosion of soft rock layers. For example, the Great Basin in the western United States formed through crustal stretching and contains hundreds of smaller valleys and salt flats. Basins act as natural collectors for water and sediment. Some, like the Sahara Desert basins, are mostly dry but may fill with water during rare heavy rains, forming temporary lakes called playas. Researchers use satellite imagery to track basin changes and sediment buildup.

These landforms interact with Earth's water cycle, climate, and living organisms. Plateaus can affect weather patterns by blocking winds, while plains support major farming regions. Basins often become sites for lakes or deserts, depending on rainfall and drainage. Studying these features provides insight into Earth's dynamic systems and helps predict future landscape changes.

Interesting Fact: The Tibetan Plateau is sometimes called the "Roof of the World" because it averages over 4,500 meters (14,800 feet) above sea level—higher than most mountain peaks!

Which process forms the Columbia Plateau?

What is the main characteristic of a plain?

Which landform is described as a low area surrounded by higher land?

What causes tectonic plateaus to form?

What does the word 'playa' mean in the context of the passage?

Based on the passage, why are plains important for agriculture?

How do basins form according to the passage?

If a scientist finds thick layers of lava rock, what type of landform might they be studying?

True or False: The Great Basin is mostly formed by volcanic lava flows.

True or False: Plateaus can have canyons cut into them by rivers over millions of years.